A backlight source is an important component part for a liquid crystal display device, and its power consumption and cost occupy a large proportion in the entire liquid crystal module.
In a backlight source circuit, the power consumption at a Light Emitting Diode LED is transformed into lights, which is an origin of the lights in the backlight source, while the power consumption in a driving circuit is transformed into the heat, which is not needed by the backlight source, and the generated heat would influence the stability as the backlight source operates. Decreasing of the power consumption in the driving circuit needs to improve an efficiency of the driving circuit as much as possible.
Generally, a backlight source driving circuit provides a constant operation current to the LED in a manner of a switch power supply. Herein, power consumptions of inductors and diodes occupy a large proportion in the backlight source driving circuit, and a decreasing of the power consumptions in these elements may provide more electrical energy to the LED and in turn realize an increasing of a driving efficiency. In a switch circuit, the diode is normally utilized as a freewheeling element, and when the diode is turned on, a certain voltage drop occurs across the diode, such that the power consumption in the diode is very large because a driving current of the entire backlight source flows through the diode.